In general, a vehicle lamp is configured to switch between a low beam and a high beam. The low beam is to irradiate a close region with a predetermined illuminance. The light distribution regulations thereof are stipulated so as not to cause glare to an opposite vehicle and a leading vehicle. The low beam is mainly used during traveling in an urban area. On the other hand, the high beam is to irradiate a front wide range and a distant region with a relatively high illuminance, and is mainly used during high-speed traveling on a road on which opposite vehicles and leading vehicles are few. Therefore, while the high beam is better in the driver's visibility, as compared to the low beam, it causes the glare to a driver of a vehicle or a pedestrian in front of the vehicle.
In recent years, there has been suggested an Adaptive Driving Beam (ADB) technology of dynamically and adaptively controlling a light distribution pattern of the high beam based on surrounding states of a vehicle. The ADB technology is to detect whether a leading vehicle, an opposite vehicle or a pedestrian is in front of the vehicle and to reduce the light in a region corresponding to the vehicle or pedestrian, thereby reducing the glare which is to be caused to the vehicle or pedestrian.
FIG. 1 is a basic block diagram of a vehicle lamp system employing ADB. A vehicle lamp system (referred to as a lamp system) 2r includes a camera 10, a controller 12 and a headlight (high beam) 14. The camera 10 is configured to acquire an image of a region in front of the vehicle. The controller 12 is configured to detect a leading vehicle, an opposite vehicle, a pedestrian and the like based on image information S1 acquired by the camera 10, and to determine a light distribution pattern including a light-on area RON in which the beam should be irradiated and a light-off area ROFF in which the beam should not be irradiated. The controller 12 is configured to generate a light distribution command S2 for instructing the light distribution pattern and to supply the same to the headlight 14. The headlight 14 is configured to irradiate a region in front of the vehicle based on the light distribution command S2 generated by the controller 12 such that a desired light distribution pattern is to be obtained (See, for example, JP-A-2013-147138).
In the lamp system 2r of FIG. 1, the mounting position precision of the camera 10 and the headlight 14 may be important. If the mounting positions thereof deviate, an area in which the light should be originally shielded is irradiated, so that the glare is caused.
For this reason, in the related art, the light-off area ROFF is set, considering the possible deviation of the mounting positions of the camera 10 and the headlight 14. Specifically, when a leading vehicle or an opposite vehicle is detected from an image of the camera 10, an area obtained by adding a margin to an area RX in which the leading vehicle or the opposite vehicle exists is set as the light-off area, so that the glare is prevented.
Incidentally, a control method of the light distribution pattern by the headlight 14 includes (1) a division method of dividing an irradiation area into a plurality of small areas and switching the light-on and light-off in each small area, (2) a scanning method of scanning a beam to a region in front of the vehicle and switching the light-on and light-off every predetermined time, and the like. The headlight 14 which is to be used for the ADB system has been developed so as to control the light distribution with higher precision. For example, in the division method, the number of divisions is increased to perform the high-precision light distribution control, and in the scanning method, a temporal resolution of the light-on/light-off switching is increased to perform the high-precision light distribution control.
When the controller 12 determines the light distribution pattern by taking a wide margin of the light-off area, considering the positional deviation, the superiority of the high-precision headlight 14 is lost, so that the headlight 14 is overengineered.